SQLite中的外鍵

我正在創建兩個表，一個用於書籍，另一個用於stores.I想要通過給Store_ID將BookStore表中的每本書鏈接到StoreTable。 Store_Id將成爲StoreTable中的主鍵。我在外鍵的語法方面遇到了問題。我還檢查了http://www.sqlite.org/foreignkeys.html以供參考，但這並沒有給我足夠的解釋。如果有人幫助我，我將非常感激。SQLite中的外鍵

public class DatabaseHelper extends SQLiteOpenHelper{ 


//Name of databases 
public static final String DATABASE_NAME = "Library.db"; 
//Version of database 
public static final int DATABASE_VERSION = 1; 

//Table of Stores 
public static final String STORE_TABLE = "Store_Table"; 
public static final String STORE_ID = "Store_ID"; 
public static final String STORE_NAME = "Store_name"; 
public static final String STORE_Address = "Store_Address"; 
public static final String STORE_LAT = "lat"; 
public static final String STORE_LNG = "lng"; 

//Table of Books 
public static final String BOOKS_TABLE = "Books_Table"; 
public static final String BOOK_ID = "Book_ID"; 
public static final String BOOK_NAME = "Book_name"; 
public static final String BOOK_AUTHOR = "Book_Author"; 
public static final String BOOKStore = "BookStore_ID"; 

//Creating Stores Table 
private static final String SQL_CREATE_TABLE_STORE = "CREATE TABLE " + STORE_TABLE + "(" 
     + STORE_ID + " INTEGER PRIMARY KEY AUTOINCREMENT, " 
     + STORE_NAME + " TEXT NOT NULL, " 
     + STORE_Address + " TEXT NOT NULL, " 
     + STORE_LAT + " TEXT NOT NULL, " 
     + STORE_LNG + " TEXT NOT NULL" 
     +");"; 
//Creating Books Table 
private static final String SQL_CREATE_TABLE_BOOKS = "CREATE TABLE " + BOOKS_TABLE + "(" 
     + BOOK_ID + " INTEGER PRIMARY KEY AUTOINCREMENT, " 
     + BOOK_NAME + " TEXT NOT NULL, " 
     + BOOK_AUTHOR + " TEXT NOT NULL, " 
//How to relate BookStore with Store_ID here? 
     +FOREIGN KEY(BOOKStore) REFERENCES STORE_TABLE(STORE_ID)); 
     +");"; 



public DatabaseHelper(Context context) { 
    super(context, DATABASE_NAME, null, DATABASE_VERSION); 
    SQLiteDatabase db = this.getWritableDatabase(); 
} 

@Override 
public void onCreate(SQLiteDatabase sqLiteDatabase) { 

    sqLiteDatabase.execSQL(SQL_CREATE_TABLE_STORE); 
    sqLiteDatabase.execSQL(SQL_CREATE_TABLE_BOOKS); 

} 

@Override 
public void onUpgrade(SQLiteDatabase sqLiteDatabase, int i, int i1) { 

    //Clear all data 
    sqLiteDatabase.execSQL("DROP TABLE IF EXISTS " + STORE_TABLE); 
    sqLiteDatabase.execSQL("DROP TABLE IF EXISTS " + BOOKS_TABLE); 

    //RECREAT THE TABLES 
    onCreate(sqLiteDatabase); 

} 
}

來源

2017-06-21 waheed abbax

這是正確的答案：

private static final String SQL_CREATE_TABLE_BOOKS = "CREATE TABLE " + BOOKS_TABLE + "(" 
     + BOOK_ID + " INTEGER PRIMARY KEY AUTOINCREMENT, " 
     + BOOK_NAME + " TEXT NOT NULL, " 
     + BOOK_AUTHOR + " TEXT NOT NULL, " 
//How to relate BookStore with Store_ID here? 
     + " FOREIGN KEY ("+ BOOKStore +") REFERENCES "+STORE_TABLE+"("+STORE_ID+"));";

來源

2017-11-14 21:27:26

我看到了CREATE TABLE聲明爲Books_Table多個問題。首先，如果要將表中的列指定爲外鍵，則首先必須存在該列。定義外鍵時，您指的是BookStore_ID列，但您從未真正定義過此列。其次，如果要將列標記爲外鍵，則有特定的語法。詳情請參閱下文。

CREATE TABLE Books_Table (
    Book_ID INTEGER PRIMARY KEY AUTOINCREMENT, 
    Book_name TEXT NOT NULL, 
    Book_Author TEXT NOT NULL, 
    BookStore_ID INTEGER, 
    CONSTRAINT fk_bookstore FOREIGN KEY (BookStore_ID) 
     REFERENCES Store_Table(Store_ID) 
);

來源

2017-06-21 08:49:44

它說，在每一個變量和每一個關鍵字「無法解析符號」。 –

然後你的Java代碼有問題。這個原始的SQL語句應該沒有錯誤地運行。 –

這並沒有顯示任何錯誤 ' （私有靜態最後絃樂SQL_CREATE_TABLE_BOOKS = 「CREATE TABLE」 + BOOKS_TABLE + 「（Book_ID INTEGER PRIMARY KEY AUTOINCREMENT，BOOK_NAME TEXT，BOOK_AUTHOR的文本，BookStore_ID整數），約束fk_bookstore外鍵（BookStore_ID ）\ n「+ 」REFERENCES Store_Table（Store_ID）「;） ' –

SQLite中的外鍵

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